The invention relates to patient support apparatus especially but not exclusively to hospital beds, patient trolleys, physiotherapy couches or the like.
It is known to have a profiling bed or trolley in which the mattress support is so arranged that it comprises three, four or more parts hinged together wherein angular adjustment of the individual parts provides an optimum position for patient comfort and/or nursing. Similarly, the mattress support may also be adjustable with respect to its height and tilt for nursing and certain medical/physiotherapy procedures. Examples of such beds are to be found in Patents EP 0488552 and EP 0498111 which show the use of powered actuators to provide articulation for variable height and tilt, and also profiling of the patient support surface.
However, these beds or trolleys, due to the location of the actuator components, do not provide a very low mattress to floor height with good ground clearance for access for patient moving, monitoring or treatment systems. The beds or trolleys have a minimum height to the top of the mattress support platform of 400 mm. The aim of the present invention is to reduce this minimum height to below 300 mm. This is an ideal height for patient entrance/exit or transfer.
In addition, because the actuators are positioned at a number of locations around the bed or trolley base frame, the associated power and control cables are an inconvenience and a potential hazard to the patient and nurse or carrier when using the bed or trolley. The power and control cables also require specific plug and socket connections that are potential hazard areas for entry of water during cleaning.
Accordingly, the invention provides a patient support apparatus comprising a base frame supporting an upper frame, the upper frame having a platform for supporting a mattress or the like, at least one powered actuator for varying the height and tilt of the upper frame and optionally at least one powered actuator for adjusting the profile of the platform wherein the said actuators are mounted centrally on the upper frame and arranged to lie substantially within the upper frame to achieve a very low minimum height of the patient support apparatus. The mounting of the height, tilt and profiling actuators centrally on the upper frame provides a compact arrangement with the actuators and associated power cables all located in one area on the upper frame. Also the arrangement of the actuators within the upper frame rather than on the base frame or in-between the base or upper frame allows the upper frame to almost meet the base frame in the lowest position for a very low mattress to floor height whilst still maintaining the desired ground clearance for access for patient moving, monitoring and treatment systems.
In a preferred embodiment the patient support apparatus comprises at least a pair of support arms interconnecting the base frame and the upper frame, each of the arms pivotally connected to each end of the base frame and extending towards the opposite end of the upper frame and connected to the upper frame to position the upper frame in a minimum position where the arms are fully collapsed to positions where the arms are elevated to varying degrees, said arms actuated by at least one powered actuator, said actuator(s) mounted centrally of the upper frame within the points of connection of the arms to the upper frame, and arranged to lie substantially within the upper frame. Preferably the support arms are collapsible to position the bed to the minimum position under the weight of the bed or trolley, without use of the powered actuators. This provides for mechanical emergency operation of the bed in the cardio-pulmonery resuscitation (CPR) position in the absence of power supply or on the absent of power failure.
Preferably, the said actuators are mounted on the same plane within the upper frame to minimise the depth/volume occupied by the actuators within the upper frame. More preferably, all of the actuators are arranged to operate in a longitudinal direction parallel to the upper frame without any pivotal movement, resulting in a structure without bending moments to the actuators and thus less wear and tear on the actuators.
Preferably, the actuators are all located in a single housing, the housing also providing structural support to the actuators. More preferably said housing is arranged to span transversely centrally of the upper frame and located almost entirely within the upper frame.
The location of all the height, tilt and profiling actuators in a single housing, within the upper frame allows for the very low mattress to floor height but also the single housing is the only enclosure that requires sealing to prevent ingress of water during cleaning or body fluids during use, as opposed to several items on a conventional hospital bed or trolley. Furthermore, with the housing providing a structural casing for all the actuators and thereby eliminating the need for individual actuator casings, the overall number of components are minimised with the consequent benefits of reduced cost of manufacture.
Preferably, the housing may be located substantially under the seat section of the platform and optionally may be integral with the seat section of the platform to provide improved structural rigidity to the upper frame.
Preferably, the actuators are controlled by control means also located within the housing. The housing may also include means to record the patients"" physical data or characteristics, for example height or weight and may include means to communicate with a patient and/or nurse interface module situated at the side or foot end of the bed.
In a preferred embodiment, load cells may be mounted on the actuators supporting the upper frame to provide an indication of load applied to the platform when a patient is lying thereon, and converted to patient weight by the control means within the housing.
Preferably, the housing could include means to illuminate the perimeter of the mattress platform on the floor, to give the patient clear vision when entering or exiting the bed when dark. Advantageously, such means could be patient or nurse controlled.
Preferably, the housing may include a pneumatic pump or means for attachment thereof to supply compressed air to operate a pressure relieving mattress supported upon the platform and/or compression garments for treatment of a patient lying upon the mattress.
Preferably, the housing as a unit may be secured to the upper frame by releasable fastenings to allow for removal of the housing from the upper frame for servicing or enhancement of the actuators and components housed within.